Burt Reynolds, who plays the tough cop, has called Cop and a Half (which opens today) a cross between Home Alone and Dirty Harry.

Accurate but not encouraging.

In any case, the movie contains precisely two comic devices.

The first of these involves having young Devon (Norman D. Golden II) repeat cop-show cliches that he has picked up from prime-time TV.

''It's a Code 3. Let's roll.''

''Let's go kick some (expletive).''

And of course, the ever-popular ''Freeze, dirtbag!''

The other device is to have Nick McKenna, the cop Reynolds plays, do a slow burn every time the kid says or does anything.

''My strong suit is not patience,'' admits the cop, who speaks for many in the audience.

Reynolds smolders so much here that you'd swear his mustache - or his rug - is on fire. But, no, that's only his cigar - to which the precocious youngster, who knows all about the hazards of secondary smoke, strenuously objects.

Cop and a Half was filmed last year in Tampa, whose ''wonderful police department'' is acknowledged in the closing credits.

The cast includes Ray Sharkey as the drug-dealing villain whom Devon helps to identify.

This scoundrel's penchant for swaggering and his fondness for '50s music bring to mind the Fonz of Happy Days, which may not be entirely coincidental since Henry Winkler is the film's director. The script is by Arne Olsen, whose principal credit so far is Dolph Lundgren's Red Scorpion.

Just about the only really enjoyable thing about Cop and a Half is Norman D. Golden II, who is genuinely cute and a pretty good little actor besides. Despite the cop-show dialogue that has been stuffed in his mouth, this kid possesses an endearing gentleness - a surprisingly rare quality among child actors.

I don't usually give out half stars, but I've decided to stretch a point and award Cop and a Half a star and a half instead of just one star (my lowest rating).

The extra half-star is for young Norman who - with any luck - will grow up to be a full star one day.